From High Performance Cookers
"Use a steamer rack to transform your boiling pot into a steaming machine! NOTE: This steamer insert is NOT a steamer basket, but a round steamer plate that is inserted in a basket. This insert has attached legs and sits 3 inches above the bottom of the basket, enabling you to fill up to 3 inches of water in the pot for steaming. By inserting one or more steamer rack shelves into the 80, 100, or 120 QT pot's basket, you turn your cooker into a multi-shelf steamer!"
Diameter Measurements:
Standard 120 QT - 19 1/2"